The main reason is that you haven't given Google or other search engines enough time to find your site.
You only created it on 25 April 2020 and it used to be reckoned that it took Google around six weeks to trawl all round the internet to see what might be new.
Have you submitted your forum to Google directly?
What have you done to promote it and ensure there are plenty of links on well respected sites that point to your forum?
Volunteer Helper - but recommending that users move off the platform!
Once the admin for GregHelp now deleted.